Fireplace heater



Sept. 21, 1937. R. w. SNYDER FIREPLACE HEATER Filed Nov. 11, 19:55

2 Sheets-Sheet l Sept. 21, 1937. A R. w. SNYDER FIREPLACE HEATER 2 Sheets- Sheet 2 Filed Nov. 11, 1935 Patented Sept. 21, 1937 FIREPLACE HEATER Ross W. Snyder, Bradenton, Fla... assignor of one-half to Robert F.

Sharp, Bradenton, Fla.

Application November 11, 1935, Serial No. 49,315

6 Claims.

Thisinvention relates to improvements in fireplace heaters wherein a hollow heating element is utilized in connection with an open fireplace for heating air and delivering it to a room.

The primary object of my invention. is to provide an improved and scientifically designed heater for using some of the formerly Wasted heat developed in an open fireplace, by causing air heated thereby to flow into a room, thereby l greatly improving the efficiency of the fireplace for heating purposes.

Another object is to provide an improved device associated with an open fireplace for directing a current of heated air into a room, to supplement i the heat normally radiated from the fireplace and improve the ventilation of the room.

A further object is to provide a device, serving as a form about which the brickwork of an open fireplace may be built, for heating and delivering .20 air to a room.

gradually decreasing in area upwardly, in order to maintain a practically constant velocity of flow of flue gases, said flue being surrounded by an air-heating compartment or conduit which gradually expands in area upwardly in accordance with thenormal expansion of the air being heated, so that the velocity of flow of heated air through the heater is substantially constant and said air. tends to force itself out of the upper end of the conduit.

With the foregoing and various other objects in .view, the invention desirably consists of certain .novel features of construction and operation, as

will be more fully described and particularly 7 pointed out in the specification and illustrated in r i the drawings;

Referring to the drawings which illustrate an embodiment of my invention, and wherein like reference-characters are used to designate like parts Figure 1 is a front elevational view of one embodiment of my fireplace heater, with the brickwork removed from a portion thereof in order tomore clearly show the construction.

Figure 2 is a vertical sectional view on the line 2-2 of Figure 1, looking in the direction of the arrows.

Figure 3 is a top plan of my fireplace heater with the brickwork removed.

Figures 4, 5 and 6 are horizontal sectional views on the correspondingly numbered lines of Figure 1, looking in the direction of the arrows and showing the heater with the'brickwork removed.

Figure 7 is a vertical sectional view corresponding to Figure 2, but showing the intermediate section of the heater detached from the associated end sections, brickwork and insulation.

Figure 8 is a bottom plan of the intermediate section of the heater shown in Figure 7.

Figure 9 is a fragmentary side elevational view of the lower portion of the complete heater, as shown in Figure 1, said view especially showing the details of the regulating shutter or damper for the air inlet from the room.

Referring to the drawings illustrating a desirable embodiment of my invention, it will be seen that my invention comprises a heating device, about whicha brick or masonry open fireplace may be built, generally designated by the reference character 1 and desirably formed of metal, for example, cast iron. For convenience in manufacture' and assembly, the device is desirably formed in a plurality of parts, such as a lower or fireplace forming part 2, an intermediate or main heat transfer part 3 and an upper hood or hot air discharge part 4. The parts are desirably formed for convenient assembly obviating leakage, and for that purpose the lower portions of the intermediate and upper parts 3 and 4 desirably have depending flanges 5 and 6 which telescope with the upper edge portions of the walls of the sections therebelow, as shown most clearly in Figure 2. In this way, the parts are readily assembled in tight-fitting relation without danger of any appreciable leakage. If desired, the telescoping joints may be sealed by insulating packing, as will be understood.

The parts of my heater are not only desirably formed for convenient assembly, but the outside surfaces thereof are desirably generally rectangular, and the main heat transfer part of generally uniform horizontal crosssection, so that brickwork or masonry I can be conveniently placed therearound. During the development of the heater being described it was found easier to build the fireplace and chimney brick 1 around such a heater than to build a fireplace and chimney, without the heater to serve as a form.

The fireplace heater I of my invention is designed for great efiiciency in the utilizationof the i heat developed in the fireplace, as when burning logs of wood 8 on andirons 9, and for that purpose desirably involves the following features:-

It is well known that as air or gas cools it contracts in volume in accordance with scientific laws. This is because the product of the pressure and volume of a gas divided by the absolute temperature is a constant. Inasmuch as the pressure of the flue gases can be assumed as substantially constant, the volume will vary inversely as the absolute temperature. Therefore, if such gases are conducted in a flue of constant area, the velocity of flow of said gases will decrease as they cool. As will be seen, especially in Figures 1 and 2, the inner portion ll] of my heater, which provides a passage for conducting the flue gases or products of combustion from the fireplace portion or combustion chamber l l to the stack l2, decreases gradually in passage area from the lower to the upper portion, and particularly that portion of the flue If) in the intermediate section 3 of the heater where the greater amount of heat-transfer occurs.

In order to provide for conducting air to my heater for absorbing heat from the flue or central portion thereof, I desirably form the heater with outer walls i3 spaced from the walls of the fiue ill so as to provide a peripheral, annular, or at least partially enclosing conduit M therearound for receiving air to be heated. The area of the conduit or air passage l gradually increases upwardly to allow for the natural expansion of the air as heated and provides for substantially uniform velocity of said air, whereby said heated air tends to force itself out of the upper end of said passage. Into this conduit I direct air from outdoors, desirably through a screen 5, a passageway or air duct I6 communicating with the generally U-shaped lower portion ll of the air compartment, illustrated most clearly in Figure 6. In order not to be obliged to take all of the air from outdoors, especially in severe weather, I provide for the recirculation of some of the air in the room, by forming one or more air intakes l8, the amount of air drawn therein being desirably controlled by shutters or dampers l9, one embodiment of which is illustrated in detail in Figure 9.

In order to efficiently utilize the heat of the fire, especially directly in the vicinity of the fuel 8 being consumed, I desirably provide a rigidifying bulge or corrugation fill in that portion of the heater defining the back wall of the fireplace H, which also prevents warping and provides a more durable construction. For further facilitating the transfer of heat from the flue if] to the surrounding air heating space, the outer surfaces of the Walls defining said flue and forming the inner surface of the air conducting chamber M, and particularly the intermediate portions forming part of the heater element 3, are desirably corrugated or formed with heat-conducting ribs or fins 2 I, which, of course, rigidify the walls, prevent warping, and make the construction more durable.

To prevent substantial loss of heat from the air-conducting passageway I l to the surrounding brickwork or masonry, the outer surface of the heater around the air passageway 54 is desirably covered with fire-proof insulation 22.

In order to hold the inner or waste gas flue Ill in position with respect to the outer or surrounding air flue M of the intermediate section 3, while not interfering with communication between all portions of the air-conducting flue,

upright webs 23 are shown for connecting said inner flue with the outer walls, said webs being shown as extending from the junctions at the front and side walls of the flue H] to the side Walls 24 of the heater section 3.

I show a damper 25 or adjustable baflle plate in the flue it above the air discharge portion 26 of the heater, said damper being controllable from one side of the fireplace, as by means of a rod 21 the inner end of which is pivoted to one arm of the bell crank 28, and the other arm of which is connected to an operating arm 29 rigid with the damper 25, by means of a connecting rod 30. Pushing in the rod 21 will move the damper 25 from the position shown in full lines to that shown in dot-dash lines, thereby controlling the amount of draft for the fire. I have found it undesirable to completely close the flue It] by the damper 25, and, therefore, said damper does not extend the full width of said flue even when in closed position, as indicated in Figure 2. A desirable proportion is for the damper to close two-thirds of the flue area, thereby avoiding the possibility of checking the draft to an extent suificient to cause smoking of the fire.

In order to control the flow of heat from the hot air discharge opening 26 to the room in which the heater is located, a damper 3|, which may comprise shutters 32 as illustrated most clearly in Figures 1 and 2, is desirably provided. These shutters desirably swing outwardly and upwardly, so that, when partially open, the heated air tends to be deflected downwardly into the room rather than upwardly against the ceiling, in order to get the greatest useful heating effect from the hot air. The hot air discharge opening 26 is, of course, desirably larger than the aggregate area of the cold air receiving openings or passages l6 and H].

The operation of my improved fireplace heater is as follows:

When no fire is in the fireplace the dampers I9 and 3i are, of course, closed unless it is desired to keep them open for ventilating purposes. When a fire is in the fireplace, the waste gases pass into the relatively large lower end of the flue I 0 and are discharged to the chimney or stack from the desirably smaller upper end thereof. The dampers or shutters l 9 and 3! are adjusted so that the desired proportion of air is allowed to pass r of. Dissipation of heat from the air being heatedis desirably retarded by the insulation 22. The heated air finally passes from the annular or peripheral heating passage I4 into the upper or hood portion 4 of the heater, discharging through the single outlet 26 through the regulating shutters 3|, at an angle to the direction of flue gas flow or in a substantially horizontal or diagonally downward direction.

A test of a heater involving my invention showed great efficiency in heating, not only the room in which the fireplace is located, but also communicating rooms, on account of the flow of air induced by discharging heated air in a generally horizontal or diagonally downward direction from above the fireplace and drawing air from the lower portion of the room adjacent said terial out of which it is formed or the exact proportions of the parts. The following claims allow for variations in design without departing from the spirit and scope of my invention.

1' claims- 1 1. In combination, a fireplace stack of generally uniform horizontal straight sided cross-section and serving as a form about which fireplace brickwork may be built, and an upwardly contracting waste gas flue mounted in said stack and at least partially spaced from the inner surfaces thereof to leave an upwardly expanding air passage therearound, so that the air in said passage is all-owed to expand as'it is heated whereby to force itself out of the upper end'of the passage,

' while the waste gases in said flue correspondingly contract as they are cooled, and maintain approximately uniform velocity.

2. In combination, a fireplace stack of generally uniform rectangular cross-section and serving as a form about which fireplace brickwork I may be built, and an upwardly contracting waste velocity.

3. In combination, a brickworkenclose-d fireplace stack of generally uniform rectangular horizontal cross-section, and an upwardly contracting waste gas flue mounted in said stack and at least partially spaced from the inner surfaces thereof to leave an upwardly expanding air passage outwardly thereof, so that air in said passage may be heated from the waste gases in said flue and force itself out of the upper end of the passage while the waste gases correspondingly contract as they are cooled, and are maintained at approximately uniform velocity.

4. In combination, a fireplace stack of generally uniform rectangular horizontal cross-section and serving as a form about which fireplace brickwork may be built, and an upwardly contracting waste gas flue mounted in said stack and at least partially, spaced from the inner surfaces of walls thereof to leave an upwardly expanding air passage therearound, and connected to intermediate portions of said walls by upright webs extending from junctions between said flue walls to corresponding side walls of said stack.

5 In combination, a fireplace heater of straight sided horizontal cross-section and serving as a form about which fireplace brick-work may be built, the lower portion of said heater being double walled on three sides and open on one side to provide a combustion chamber, the inner walls extending to form an upwardly contracting waste gas flue and the outer walls formed with laterally opening passages to admit air between said walls which form an upwardly flaring air warm- 1 ing space terminating in an opening for the discharge of heated air into a room, so that the air in said space is allowed to expand as it is heated and force itself out of said opening while the waste gases contract as they are cooled in the flue.

6. In combination, a fireplace heater of generally straight sided cross-section, having walls,

and serving as a form about which fireplace brick-work may be built, and other walls forming an upwardly contracting waste gas flue generally straight sided in horizontal section mounted within said first-mentioned walls, and at least partially spaced from the inner surfaces thereof, to leave an upwardly flaring air passage generally straight sided in horizontal section, so that the air in said passage is allowed to expand as it I is heated, whereby to forceitself out of the upper end of the passage, while the waste gases in said flue correspondingly contract as they are cooled, and maintain approximately uniform velocity.

ROSS W. SNYDER. 

